# init(describing:) Creates a string representing the given value. ``` init(describing instance: Subject) ``` ## Discussion Use this initializer to convert an instance of any type to its preferred representation as a `String` instance. The initializer creates the string representation of `instance` in one of the following ways, depending on its protocol conformance: - If `instance` conforms to the `TextOutputStreamable` protocol, the result is obtained by calling `instance.write(to: s)` on an empty string `s`. - If `instance` conforms to the `CustomStringConvertible` protocol, the result is `instance.description`. - If `instance` conforms to the `CustomDebugStringConvertible` protocol, the result is `instance.debugDescription`. - An unspecified result is supplied automatically by the Swift standard library. For example, this custom `Point` struct uses the default representation supplied by the standard library. ``` struct Point { let x: Int, y: Int } let p = Point(x: 21, y: 30) print(String(describing: p)) // Prints "Point(x: 21, y: 30)" ``` After adding `CustomStringConvertible` conformance by implementing the `description` property, `Point` provides its own custom representation. ``` extension Point: CustomStringConvertible { var description: String { return "(\(x), \(y))" } } print(String(describing: p)) // Prints "(21, 30)" ``` --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)